Expandable interbody device

ABSTRACT

An expandable interbody device for placement between adjacent vertebrae having an upper structure, a lower structure and a screw mechanism, wherein actuation of the screw mechanism moves the upper and lower structures between a collapsed configuration and an expanded configuration. A deployment tool couples to the expandable interbody device for positioning the device between adjacent vertebrae, actuating the screw mechanism and delivering a material to a chamber of the expandable interbody device.

CROSS-REFERENCE TO RELATED APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 CFR 1.57,including U.S. patent application Ser. No. 15/608,079, filed May 30,2017, U.S. patent application Ser. No. 14/333,336, filed Jul. 16, 2014,now U.S. Pat. No. 9,668,876, U.S. Provisional Application No.61/912,360, filed Dec. 5, 2013 and U.S. Provisional Application No.61/912,432, filed Dec. 5, 2013.

BACKGROUND Field

The present disclosure generally relates to the field of spinalorthopedics, and more particularly to expandable spinal implants forplacement in intervertebral spaces between adjacent vertebrae.

Related Art

The spine is a flexible structure that extends from the base of theskull to the tailbone. The weight of the upper body is transferredthrough the spine to the hips and the legs. The spine contains aplurality of bones called vertebrae. The vertebrae are hollow andstacked one upon the other, forming a strong hollow column for support.The hollow core of the spine houses and protects the nerves of thespinal cord. The spine is held upright through the work of the backmuscles, which are attached to the vertebrae. While the normal spine hasno side-to-side curve, it does have a series of front-to-back curves,giving it a gentle “S” shape.

Each vertebra is separated from the vertebra above or below by acushion-like, fibrocartilage called an intervertebral disc. The discsact as shock absorbers, cushioning the spine, and preventing individualbones from contacting each other. In addition, intervertebral discs actas a ligament that holds vertebrae together. Intervertebral discs alsowork with the facet joint to allow for slight movement of the spine.Together, these structures allow the spine to bend, rotate and/or twist.

The spinal structure can become damaged as a result of degeneration,dysfunction, disease and/or trauma. More specifically, the spine mayexhibit disc collapse, abnormal curvature, asymmetrical disc spacecollapse, abnormal alignment of the vertebrae and/or general deformity,which may lead to imbalance and tilt in the vertebrae. This may resultin nerve compression, disability and overall instability and pain. Ifthe proper shaping and/or curvature are not present due to scoliosis,neuromuscular disease, cerebral palsy, or other disorder, it may benecessary to straighten or adjust the spine into a proper curvature withsurgery to correct these spinal disorders.

Surgical treatments may involve manipulation of the spinal column byattaching a corrective device, such as rods, wires, hooks or screws, tostraighten abnormal curvatures, appropriately align vertebrae of thespinal column and/or reduce further rotation of the spinal column. Thecorrect curvature is obtained by manipulating the vertebrae into theirproper position and securing that position with a rigid system of screwsand rods. The screws may be inserted into the pedicles of the vertebraeto act as bone anchors, and the rods may be inserted into heads of thescrews. Two rods may run substantially parallel to the spine and securethe spine in the desired shape and curvature. Thus the rods, which areshaped to mimic the correct spinal curvature, force the spine intoproper alignment. Bone grafts are then placed between the vertebrae andaid in fusion of the individual vertebrae together to form a correctlyaligned spine.

Other ailments of the spine result in degeneration of the spinal disc inthe intervertebral space between adjacent vertebrae. Disc degenerationcan cause pain and other complications. Conservative treatment caninclude non-operative treatment requiring patients to adjust theirlifestyles and submit to pain relievers and a level of underlying pain.Operative treatment options include disc removal. This can relieve painin the short term, but also often increases the risk of long-termproblems and can result in motor and sensory deficiencies resulting fromthe surgery. Disc removal and more generally disc degeneration diseaseare likely to lead to a need for surgical treatment in subsequent years.The fusion or fixation will minimize or substantially eliminate relativemotion between the fixed or fused vertebrae. In surgical treatments,interbody implants may be used to correct disc space collapse betweenadjacent vertebra, resulting in spinal fusion of the adjacent vertebra.

A fusion is a surgical method wherein two or more vertebrae are joinedtogether (fused) by way of interbody implants, sometimes with bonegrafting, to form a single bone. The current standard of care forinterbody fusion requires surgical removal of all or a portion of theintervertebral disc. After removal of the intervertebral disc, theinterbody implant is implanted in the interspace. In many cases, thefusion is augmented by a process called fixation. Fixation refers to theplacement of screws, rods, plates, or cages to stabilize the vertebraeso that fusion can be achieved.

Interbody implants must be inserted into the intervertebral space in thesame dimensions as desired to occupy the intervertebral space after thedisc is removed. This requires that an opening sufficient to allow theinterbody implant must be created through surrounding tissue to permitthe interbody implant to be inserted into the intervertebral space. Insome cases, the intervertebral space may collapse prior to insertion ofthe interbody implant. In these cases, additional hardware may berequired to increase the intervertebral space prior to insertion of theimplant.

In addition, minimally invasive surgical techniques have been used onthe spine. Under minimally invasive techniques, access to theintervertebral space is taken to reach the spine through smallincisions. Through these incisions, discs are removed and an interbodyimplant is placed in the intervertebral disc space to restore normaldisc height. Minimally invasive spine surgery offers multiple advantagesas compared to open surgery. Advantages include: minimal tissue damage,minimal blood loss, smaller incisions and scars, minimal post-operativediscomfort, and relative quick recovery time and return to normalfunction.

SUMMARY

It would be desirable to insert an interbody device with a first smallerdimension into an intervertebral space and once in place, deploy to asecond, relatively larger dimension to occupy the intervertebral space.This first smaller dimension can permit the use of minimally invasivesurgical techniques for easy access to the intervertebral space, whichcan cause less disruption of soft and boney tissue in order to get tothe intervertebral space. The interbody device may be implanted with orwithout the need of additional hardware.

Disclosed is an expandable interbody device that is configured to havean initial collapsed configuration having a first height suitable forbeing inserted into an intervertebral space between a pair of adjacentvertebrae, and an expanded configuration having a second height that isgreater than the first height. The implant can be expanded from theinitial collapsed configuration to the expanded configuration in-situ.The expanded configuration can provide support to the adjacent vertebraewhile bone fusion occurs and can also provide rigid support between theadjacent vertebrae that withstands compressive forces. In someconfigurations, the expandable interbody device can help increase thedistance between the adjacent vertebrae. By inserting the expandableinterbody device in the initial collapsed configuration into theintervertebral space, it is possible to perform the surgerypercutaneously with minimal disruption to tissues surrounding thesurgical site and intervening soft tissue structures. The expandableinterbody device can be implanted through a minimally invasive or anopen wound procedure.

In accordance with at least one of the embodiments disclosed herein, anexpandable interbody device for placement between adjacent vertebrae cancomprise an upper structure comprising an upper proximal angled surfaceand an upper distal angled surface; a lower structure comprising a lowerproximal angled surface and a lower distal angled surface, the lowerstructure configured to slideably couple with the upper structure; and ascrew mechanism between the upper structure and the lower structure. Thescrew mechanism can comprise a proximal section comprising a proximalfrustoconical surface, a distal section comprising a distalfrustoconical surface, and a coupler comprising a proximal sideconfigured to engage the proximal section and a distal side configuredto engage the distal section, wherein the proximal section and thedistal section are configured to rotate as a unit to change a length ofthe screw mechanism from a first length to a second length. The proximalfrustoconical surface can be configured to engage the upper proximalangled surface and the lower proximal angled surface, and the distalfrustoconical surface can be configured to engage the upper distalangled surface and the lower distal angled surface to move the upperstructure and the lower structure from a first distance to a seconddistance.

The coupler can further comprise at least one anti-rotational featureconfigured to engage the upper structure or lower structure to preventthe coupler from rotating when the proximal section and the distalsection are rotated.

The proximal section can comprise first threads wound in a firstdirection configured to engage a proximal threaded hole in the coupler,and the distal section can comprise second threads wound in a seconddirection, opposite the first direction, configured to engage a distalthreaded hole in the coupler. In some embodiments, the first threads andthe second threads have an equal pitch, such that when the screwmechanism is actuated, a proximal end of the interbody device changesheight at the same rate as a distal end of the interbody device. Inother embodiments, the first threads and the second threads have adifferent pitch, such that when the screw mechanism is actuated, aproximal end of the interbody device changes height at a different ratethan a distal end of the interbody device.

The upper structure and lower structure can further comprise a pluralityof protrusions or teeth. The upper structure and/or the lower structurecan comprise vertebrae engagement surfaces with a porous or roughenedsurface. For example, the vertebrae engagement surfaces can comprise atitanium coating.

In some embodiments, the proximal section comprises at least one hole influid communication with a drive interface and an interior cavity of theinterbody device. The interbody device can further comprise at least onerecess configured to couple with a deployment tool, the at least onerecess comprising a hole in fluid communication with an interior cavityof the interbody device.

In some embodiments, the distal section comprises a keyed shaftconfigured to slideably engage with a matching keyed bore on theproximal section.

In accordance with at least one of the embodiments disclosed herein, anexpandable interbody device for placement between adjacent vertebrae cancomprise an upper structure, a lower structure configured to slideablycouple with the upper structure, and a screw mechanism between the upperstructure and the lower structure, the screw mechanism comprising aproximal section and a distal section that are configured to rotate as aunit to change a length of the screw mechanism from a first length to asecond length, wherein the change in the length of the screw mechanismcauses the distance between the upper structure and the lower structureto change from a first distance to a second distance to form a chamberto be filled by one or more of fluids, medication, bone graft material,allograft and Demineralized Bone Matrix.

In accordance with at least one of the embodiments disclosed herein, akit for performing spinal stabilization can comprise an expandableinterbody device for placement between adjacent vertebrae, wherein in anexpanded configuration the expandable interbody device comprises achamber, and a deployment tool for delivering the expandable interbodydevice between adjacent vertebrae, the deployment tool comprising adistal portion that is releasably attachable to the expandable interbodydevice and a proximal portion configured to extend outside a surgicalincision. The proximal portion can comprise an opening to a channel thatextends through the deployment tool and is in fluid communication withthe distal portion of the deployment tool, the channel capable oftransporting a material from outside the incision into the chamber ofthe expandable interbody device.

In some embodiments, a proximal section of the expandable interbodydevice comprises at least one hole in fluid communication with thechamber. The expandable interbody device can further comprise at leastone recess with a hole that is in fluid communication with the chamber.The deployment tool can comprise arms that are configured to attach tothe at least one recess and further comprise one or more channelsextending to the tips of the arms to deliver material through the atleast one recess into the chamber of the expandable interbody device.

In accordance with at least one of the embodiments disclosed herein, amethod of implanting an expandable interbody device between adjacentvertebrae can comprise positioning the expandable interbody devicebetween adjacent vertebrae. The expandable interbody device can comprisean upper structure, a lower structure configured to slideably couplewith the upper structure, and a screw mechanism between the upperstructure and the lower structure. The method can further compriserotating the screw mechanism to change a length of the screw mechanismfrom a first length to a second length which causes the distance betweenthe upper structure and the lower structure to change from a firstdistance to a second distance to form a chamber, and injecting materialinto the chamber.

In some embodiments, the first distance corresponds to a collapsedconfiguration with the upper structure adjacent the lower structure andthe second distance corresponds to an expanded configuration with theupper structure separated from the lower structure.

The screw mechanism can comprise a proximal section comprising aproximal frustoconical surface, a distal section comprising a distalfrustoconical surface, and a coupler comprising a proximal sideconfigured to engage the proximal section and a distal side configuredto engage the distal section.

The material can be one or more of fluids, medication, bone graftmaterial, allograft and Demineralized Bone Matrix.

In some embodiments, the expandable interbody device can be positionedbetween the adjacent vertebrae using a deployment tool that extends fromthe vertebrae to outside an incision.

The step of injecting the material can comprise delivering the materialthrough a channel extending through the deployment tool.

In accordance with at least one of the embodiments disclosed herein, anexpandable interbody device for placement between adjacent vertebrae cancomprise an outer structure having a central opening and front and backsides with opposed front and back openings, an inner structureconfigured to slideably fit vertically within the outer structurecentral opening, the inner structure having a central opening and frontand back sides with opposed front and back threaded holes axiallyaligned with the opposed front and back openings of the outer structure,and a variable length screw mechanism having proximal and distal headsslideably engaged to the front and back openings of the outer structure,and proximal and distal threaded shafts threadably coupled to the frontand back threaded holes of the inner structure, wherein rotation of thescrew mechanism changes a length of the screw mechanism from a firstlength to a second length and the proximal and distal heads compressagainst the front and back openings resulting in vertical translation ofthe inner structure relative to the outer structure from a first heightto a second height.

The first height can be a collapsed configuration with the innerstructure within the outer structure central opening and the secondheight can be an expanded configuration with the inner structureextending vertically out of the outer structure central opening.

The threaded shafts can comprise proximal threads threadably coupled tothe front threaded hole with first threads in a first direction, anddistal threads threadably coupled to the back threaded hole with secondthreads in a second direction, opposite the first direction, such thatwhen the screw mechanism is rotated, the length of the screw mechanismincreases or decreases. In some embodiments, the first and secondthreads have an equal pitch, such that when the screw mechanism isrotated the vertical translation of a proximal end and a distal end ofthe inner structure moves at a same rate relative to a proximal end anda distal end of the outer structure. In other embodiments, the first andsecond threads have a different pitch, such that when the screwmechanism is rotated the vertical translation of a proximal end of theinner structure relative to the outer structure moves at a differentrate than a distal end of the inner structure relative to the outerstructure.

In some embodiments, the front and back openings of the outer structurecomprise ramp portions and the proximal and distal heads of the variablelength screw mechanism can be configured to engage and slide along theramp portions during translation of the inner structure relative to theouter structure. In other embodiments, the front and back openings ofthe outer structure have non-complementary engagement surfaces with theproximal and distal heads of the variable length screw mechanism, andthe proximal and distal heads of the variable length screw mechanism areconfigured to engage and slide along the non-complementary engagementsurfaces during translation of the inner structure relative to the outerstructure.

The interbody device can further comprise a keyed internal bore on thedistal end of the proximal shaft, and a keyed outer surface on theproximal end of the distal shaft configured to slidingly engage with thekeyed internal bore of the proximal shaft, wherein the keyed outersurface slides within the keyed internal bore to allow the screwmechanism to have a variable length. The outer structure and innerstructure can further comprise a plurality of protrusions or teeth.

In some embodiments, the vertebrae engagement surfaces comprise a porousor roughened surface that may be formed of a porous material, coatedwith a porous material, or chemically etched to form a porous orroughened surface with pores for bone growth with the adjacent vertebra.

In accordance with at least one of the embodiments disclosed herein, anexpandable interbody device for placement between adjacent vertebrae cancomprise an outer structure having an outer wall enclosing a centralopening, the outer wall having front and back sides with opposed frontand back openings, an inner structure having an inner wall with a lowerflanged portion enclosing a central opening, the inner wall beingconfigured to slideably fit vertically within the outer structurecentral opening, the inner wall having front and back slots with rampsproximate the slots within the inner structure central opening, thefront and back slots being axially aligned with the opposed front andback openings of the outer structure, and a screw mechanism coupled tothe inner and outer structures. The screw mechanism can comprise a shaftwith proximal and distal portions, and proximal and distal threadedramped components threadably coupled to the proximal and distalportions, the ramped components being configured to slideably engage theramps on the front and back sides of the inner structure duringexpansion of the screw mechanism. Rotation of the expansion screwmechanism can change a distance between the proximal and distal rampedcomponents from a first length to a second length and the proximal anddistal ramped components slide against the front and back rampsresulting in vertical translation of the inner structure relative to theouter structure from a first height to a second height.

The proximal and distal portions of the shaft can comprise proximal anddistal ends positioned within the front and back openings of the outerstructure. A proximal end of the shaft can comprise a tool engagementportion.

The shaft can comprise proximal threads threadably coupled to theproximal threaded ramped component with first threads in a firstdirection, and distal threads threadably coupled to the distal threadedramped component with second threads in a second direction, opposite thefirst direction, such that when the screw mechanism is rotated, thedistance between the proximal and distal ramped components increases ordecreases.

In some embodiments, the first and second threads have an equal pitch,such that when the screw mechanism is rotated the vertical translationof a proximal end and a distal end of the inner structure moves at asame rate relative to a proximal end and a distal end of the outerstructure. In other embodiments, the first and second threads havedifferent pitches, such that when the screw mechanism is rotated thevertical translation of a proximal end of the inner structure relativeto the outer structure moves at a different rate than a distal end ofthe inner structure relative to the outer structure.

The outer structure and inner structure can further comprise a pluralityof protrusions or teeth. The vertebrae engagement surfaces can comprisea porous or roughened surface that may be formed of a porous material,coated with a porous material, or chemically etched to form a porous orroughened surface with pores for bone growth with the adjacent vertebra.

In accordance with at least one of the embodiments disclosed herein, adeployment tool for delivering an expandable interbody device betweenadjacent vertebrae can comprise a distal portion configured toreleasably couple to the expandable interbody device, a proximal portioncomprising a mechanism for coupling and releasing the expandableinterbody device, and an actuation device capable of expanding theinterbody device from a first configuration to a second configuration,wherein the proximal portion is configured to extend outside a surgicalincision, wherein the proximal portion comprises an opening to a channelthat extends through the deployment tool and is in fluid communicationwith the distal portion of the deployment tool, the channel capable oftransporting a material from outside the incision into the expandableinterbody device.

The distal portion can comprise arms configured to couple to at leastone recess on the expandable interbody device. The arms can comprise oneor more channels extending to the tips of the arms to deliver materialthrough the at least one recess into a chamber of the expandableinterbody device. The actuation device can comprise a shaft that extendsthrough the deployment tool to drive the expandable interbody device atthe distal portion by manipulating an actuator at the proximal portion.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments and modifications thereof will become apparent tothose skilled in the art from the detailed description herein havingreference to the figures that follow, of which:

FIG. 1 is a perspective view showing an expandable interbody device in acollapsed configuration, according to an embodiment of the presentinvention.

FIG. 2 is a perspective view showing the expandable interbody device ofFIG. 1 in an expanded configuration.

FIG. 3 is a cross-sectional view of the expandable interbody device ofFIG. 1 in a collapsed configuration.

FIG. 4 is a cross-sectional view of the expandable interbody device ofFIG. 2 in an expanded configuration.

FIG. 5 is a perspective exploded view showing the expandable interbodydevice of FIG. 1, including the outer structure, inner structure andscrew mechanism.

FIG. 6 is a perspective exploded view showing the expandable interbodydevice of FIG. 1 with the screw mechanism assembled with the innerstructure prior to assembly into the outer structure.

FIG. 7 is a perspective view showing an expandable interbody device in acollapsed configuration, according to another embodiment of the presentinvention.

FIG. 8 is a perspective view showing the expandable interbody device ofFIG. 7 in an expanded configuration.

FIG. 9 is a cross-sectional view of the expandable interbody device ofFIG. 7 in a collapsed configuration.

FIG. 10 is a cross-sectional view of the expandable interbody device ofFIG. 8 in an expanded configuration.

FIG. 11 is a perspective exploded view showing the expandable interbodydevice of FIG. 7, including the outer structure, inner structure andscrew mechanism.

FIG. 12 is a perspective view showing an expandable interbody device ina collapsed configuration, according to another embodiment of thepresent invention.

FIG. 13 is a top view of the expandable interbody device of FIG. 12.

FIG. 14 is a bottom view of the expandable interbody device of FIG. 12.

FIG. 15 is a side view of the expandable interbody device of FIG. 12.

FIG. 16 is a front view of the expandable interbody device of FIG. 12.

FIG. 17 is a rear view of the expandable interbody device of FIG. 12.

FIG. 18 is a perspective view showing the expandable interbody device ofFIG. 12 in an expanded configuration.

FIG. 19 is a perspective exploded view showing the expandable interbodydevice of FIG. 12, including the upper structure, lower structure andscrew mechanism.

FIG. 20 is a cross-sectional view of the expandable interbody device ofFIG. 12 in a collapsed configuration.

FIG. 21 is a cross-sectional view of the expandable interbody device ofFIG. 18 in an expanded configuration.

FIG. 22 is a perspective view of the expandable interbody device of FIG.18 coupled to a deployment tool and being implanted between adjacentvertebrae.

FIG. 23 is a top view of the expandable interbody device and deploymenttool of FIG. 22.

FIG. 24 is a top view of the shaft, handle and arms of the deploymenttool of FIG. 22.

FIG. 25A is a close-up top view of the arms of the deployment tool ofFIG. 22 in an open configuration.

FIG. 25B is a close-up top view of the arms of the deployment tool ofFIG. 22 in a closed configuration.

FIG. 26 is a close-up perspective view of the expandable interbodydevice and deployment tool of FIG. 22.

FIG. 27 is a perspective view of an actuation device of the deploymenttool of FIG. 22.

FIG. 28 is a cross-sectional top view of the deployment tool of FIG. 22.

FIG. 29 is a close-up cross-sectional view of the expandable interbodydevice and deployment tool showing fluid delivery through the screwmechanism.

FIG. 30 is a side view of the proximal section of the screw mechanism ofFIG. 19.

FIG. 31 is a rear view of the proximal section of the screw mechanism ofFIG. 19.

FIG. 32 is a cross-sectional view of the expandable interbody device anddeployment tool showing fluid delivery through channels in the deliverytool, according to another embodiment of the present invention.

DETAILED DESCRIPTION

An expandable interbody device can be configured to have an initialcollapsed configuration having a first height suitable for beinginserted into an intervertebral space between a pair of adjacentvertebrae, and an expanded configuration having a second height that isgreater than the first height. The implant can be expanded from theinitial collapsed configuration to the expanded configuration in-situ.The use of a small interbody implant which may be expanded in-situallows the possibility of performing the surgery percutaneously withminimal disruption to tissues surrounding the surgical site andintervening soft tissue structures, through a minimally invasive or openprocedure. The expandable interbody device of the present disclosure caninclude features that reduce displacement of soft tissue and structuresduring placement of the expandable interbody device while providingsupport after placement to the adjacent vertebrae while bone fusionoccurs. The expandable interbody device includes a collapsedconfiguration with dimensions that can allow insertion of the expandableinterbody device between the vertebrae. Once the expandable interbodydevice is positioned in a desired location between the vertebrae, theexpandable interbody device may be expanded to an expandedconfiguration. The expanded configuration can increase the distancebetween the adjacent vertebrae and provide support to the adjacentvertebrae while bone fusion occurs. The expanded configuration can alsoprovide rigid support between the adjacent vertebrae that withstandscompressive forces. The expandable interbody device of the presentdisclosure may sometimes be referred to as an expandable interbodyimplant, expandable interbody spacer or expandable corpectomy device,all of which are envisioned for the present disclosure.

Several non-limiting embodiments will now be described with reference tothe figures, wherein like numerals reflect like elements throughout. Theterminology used in the description presented herein is not intended tobe interpreted in any limited or restrictive way, simply because it isbeing utilized in conjunction with a detailed description of certainspecific embodiments. Furthermore, some embodiments may include severalnovel features, no single one of which is solely responsible for itsdesirable attributes or which is essential to the devices and methodsdescribed herein.

The words proximal and distal are applied herein to denote specific endsof components of the instrument described herein. A proximal end refersto the end of a component nearer to an operator of the instrument whenthe instrument is being used. A distal end refers to the end of acomponent further from the operator and extending towards the surgicalarea of a patient and/or the implant. The words top, bottom, left,right, upper and lower are used herein to refer to sides of the devicefrom the described point of view. These reference descriptions are notintended to limit the orientation of the implanted interbody device andthe device can be positioned in any functional orientation. For example,in some configurations, the interbody device can be used in anupside-down orientation from the specific orientation described herein.

Referring now to FIGS. 1-6, an expandable interbody device 100 can be aspinal implant that includes an outer structure 102, an inner structure104, and a screw mechanism 106. The expandable interbody device 100 canbe movable between a collapsed configuration (shown in FIG. 1) to anexpanded configuration (shown in FIG. 2) utilizing the screw mechanism106.

The outer structure 102 can include a top surface 108, a bottom surface110, a front side 112, a back side 114, and left and right sides 116. Acombination of the sides 112, 114 and 116 forms a wall that encloses acentral opening 118. The front side 112, back side 114, left and rightsides 116 may have a varying height, length, thickness, and/or curvatureradius. The left and right sides 116 may include longitudinal openings,slots or trenches 120 configured to interface with an insertion and/ordeployment tool (not shown) during implantation and deployment of thedevice from the collapsed configuration to the expanded configuration.In some embodiments, the front side 112 and the back side 114 includeslots 122 having inwardly facing ramp portions 124 on the outer surfacesproximate the slots 122. The slots 122 and ramp portions 124 caninterface with the screw mechanism 106. As shown in FIGS. 3 and 4, theramp portions 124 slant inward from the bottom toward the top.

In other embodiments not shown, the front side 112 and the back side 114may include non-ramp features that interface with the screw mechanism106 to translate inner structure 104 relative to the outer structure 102from the collapsed configuration to the expanded configuration. Forexample, as long as the screw mechanism 106 head geometry and the slots122 or non-ramp features have non-complimentary surfaces, the inner andouter structures may translate and expand. For example, the contactsurface of the screw head may be conical or spherical and the outerstructure may have a bore with a sharp ledge. As the screw head is drawntoward that ledge, the inner and outer structures may translate andexpand.

The inner structure 104 can include a top surface 126, a bottom surface128, a front side 130, a back side 132, and left and right sides 134. Acombination of the sides 130, 132 and 134 forms an outer wall and innerwall that can enclose a central opening 136. The central opening 136 canbe configured to receive bone graft material such as allograft and/orDemineralized Bone Matrix (“DBM”) packing. In some embodiments, theinner structure 104 may not have a central opening 136 and the topsurface 126 can be closed. The inner structure 104 outer wall can beconfigured to slideably fit within the central opening 118 of the outerstructure 102. The front side 130 can include a distal threaded hole 140and the back side 132 can include a proximal threaded hole 138 thatinterface with the screw mechanism 106 and are longitudinally alignedwith the slots 122 of the outer structure 102. The threaded holes 138,140 can have threads in opposite directions, one having a left handthread and the other a right hand thread. With matching opposite threadson the screw mechanism 106, the screw mechanism 106 can contract orextend when turned to expand or collapse the interbody device, asdiscussed in more detail below. The front side 130, back side 132, leftand right sides 134 may have a varying height, length, thickness, and/orcurvature radius. In some embodiments, when the inner structure 104 ispositioned within the outer structure 102, the height and/or curvatureradius of the top surfaces 108, 126, and bottom surfaces, 110, 128, ofeach should be approximately the same, as shown in FIGS. 1 and 3. Inother embodiments, the height and/or curvature radius of each may bedifferent.

The top surfaces 108, 126 and the bottom surfaces 110, 128 of the outerand inner structures 102, 104 can include a plurality of protrusions orteeth 142 (hereinafter, referred to as “teeth”). Teeth 142 can beconfigured to be spaced throughout the top surfaces 108, 126 and thebottom surfaces 110, 128. As can be understood by one skilled in theart, the teeth 142 can be configured to have variable thickness, height,and width as well as angles of orientation with respect to surfaces 108,126 and 110, 128. The teeth 142 can be further configured to provideadditional support after the expandable interbody device 100 isimplanted in the intervertebral space of the patient. The teeth 142 canreduce movement of the outer structure 102 and inner structure 104 withthe vertebrae and create additional friction between the vertebrae andthe outer structure 102 and inner structure 104.

In some embodiments, the teeth 142 on the top surfaces 108, 126 and thebottom surfaces 110, 128 can be configured to match when the outerstructure 102 and inner structure 104 are joined in the collapsedconfiguration, as shown in FIG. 1. In other embodiments, the teeth 142on the top surface 108 and the bottom surface 110 of the outer structure102 may have different spacing, configuration, thickness, height, andwidth as well as angles of orientation with respect to the teeth 142 onthe top surface 126 and the bottom surface 128 of the inner structure104. In other embodiments, the outer structure 102 and the innerstructure 104 may only have the teeth 142 on surfaces that contact thelower and upper vertebrae in the expanded configuration. For example,the outer structure 102 may only have teeth 142 on the bottom surface incontact with the lower vertebrae while the inner structure 104 may onlyhave the teeth 142 on the top surface 126 in contact with the uppervertebrae.

In some embodiments, the top surfaces 108, 126 and the bottom surfaces110, 128 may be a porous or roughened surface, for example, they may beformed of a porous material, coated with a porous material, orchemically etched to form a porous or roughened surface with pores thatparticipate in the growth of bone with the adjacent vertebra.

As shown in the figures, the screw mechanism 106 can include a proximalsection 150 and a distal section 152 loosely coupled in a keyedconfiguration, such that when the proximal section 150 is rotated, thedistal section 152 also rotates as a unit. For example, the distalsection 152 may have a keyed shaft outer surface that slideably engagesa bore on the proximal section 150 having a matching keyed innersurface. Therefore, the distal section 152 does not have to be rigidlyconnected to the proximal section 150. One skilled in the art mayappreciate that any suitable shapes or geometric configurations for akeyed connection between the proximal and distal sections 150, 152 maybe included in the screw mechanism 106 to achieve the desired results.

In use, the screw mechanism 106 engages the outer structure 102 andinner structure 104 such that when it is rotated, the inner structure104 translates relative to the outer structure 102 from the collapsedconfiguration to the expanded configuration. If desired, the screwmechanism 106 may be rotated in the opposite direction to translate theinner structure 104 from the expanded configuration back to thecollapsed configuration. This allows the expandable interbody device 100to be moved to another location or repositioned if it is expanded in thewrong location and needs to be collapsed prior to moving orrepositioning.

The proximal section 150 and the distal section 152 may be fabricatedfrom any biocompatible material suitable for implantation in the humanspine, such as metal including, but not limited to, titanium and itsalloys, stainless steel, surgical grade plastics, plastic composites,ceramics, bone, or other suitable materials. In some embodiments, theproximal section 150 and the distal section 152 may be formed of aporous material that participates in the growth of bone with theadjacent vertebral bodies. In some embodiments, the proximal section 150and the distal section 152 may include a roughened surface that iscoated with a porous material, such as a titanium coating, or thematerial may be chemically etched to form pores that participate in thegrowth of bone with the adjacent vertebra. In some embodiments, onlyportions of the proximal section 150 and the distal section 152 may beformed of a porous material, coated with a porous material, orchemically etched to form a porous surface, such as the upper and lowersurfaces that contact the adjacent vertebra are roughened or porous. Insome embodiments, the surface porosity may be between 50 and 300microns.

The proximal section 150 can include a shaft 154 with an internal bore156 extending along its longitudinal axis. In some embodiments, shaft154 has a cylindrical outer surface and the internal bore has anon-cylindrical surface or keyed surface, such as a square or hexagonalinner surface. The proximal section 150 can also include an externalscrew threaded portion 158 configured to couple with the proximalthreaded hole 138 of the inner structure 104. The proximal end of theshaft can include a proximal circular head 160 adapted to receive adriving tool for rotating or driving the proximal section 150, and thedistal end of the shaft 154 can be configured to receive the keyed shaftportion of the distal section 152 within the internal bore 156. Betweenthe external screw thread portion 158 and the head 160 can be acylindrical engagement portion 162 configured to fit within the slot 122of the outer structure 102. The distal portion of the head 160 can havea spherical surface 164 configured to engage and slide along theproximal curved or ramp portion 124 of the outer structure 102.

The distal section 152 can include a distal circular head 166, externalscrew threaded portion 168 configured to couple with the distal threadedhole 140 of the inner structure 104, a cylindrical engagement portion162 positioned between the distal head 166 and external screw threadportion 168 configured to fit within the distal slot 122 of the outerstructure 102, and a keyed shaft 170 portion. The keyed shaft 170portion can be configured to slideably fit within the internal bore 156of the proximal section 150. When joined, the keyed shaft 170 portionand internal bore 156 act as a keyed shaft and sleeve arrangement, suchthat when the proximal section 150 is rotated, the distal section 152also rotates as a unit. The proximal portion of the head 166 can have aspherical surface 172 configured to engage and slide along the distalcurved or ramp portion 124 of the outer structure 102, as illustrated inFIGS. 3 and 4.

As mentioned above, the external screw threaded portions 158, 168 of thescrew mechanism 106 can match the threaded holes 138, 140 of the innerstructure 104. Since threaded holes 138, 140 have thread patterns inopposite directions, the external screw thread portions 158, 168 mayalso have matching thread patterns in opposite directions. In someembodiments, the threaded holes and external screw thread portions mayhave equal pitch, such that during expansion, the proximal and distalend of the outer structure 102 and inner structure 104 translate or moveat the same rate. In other embodiments, the proximal threaded hole andproximal external screw thread portion may have a different pitch thanthe distal threaded hole and distal external screw thread portion, suchthat during expansion, the proximal and distal ends of the outerstructure 102 and inner structure 104 translate or move at differentrates. For example, the proximal end of the outer structure 102 andinner structure 104 may translate or move at a first rate of speed andthe distal end of the outer structure 102 and inner structure 104 maytranslate or move at a second rate of speed. The first rate of speed maybe faster or slower than the second rate of speed. This allows for someangularity between the outer structure 102 and inner structure 104during expansion. The difference between the first and second rates ofspeed allows the user to select an expandable interbody device 100 thathas some angulation after expansion to account for the lordoticcurvature of the spine.

When the screw mechanism 106 is coupled to the inner structure 104 itmay vary in length during interbody expansion (as shown in FIGS. 3 and4). Initially, the length of the screw mechanism 106 can be L1 in thecollapsed configuration, shown in FIG. 3. As the screw mechanism 106 isrotated in a first direction, it acts like a compression screw and thelength of the screw mechanism 106 contracts to L2 in the expandedconfiguration, shown in FIG. 4, due to the threads on the proximal anddistal sections being threaded in opposite directions. By reversingrotation of the screw mechanism 106 in a second direction, opposite thefirst, the screw mechanism 106 may extend in length from L2 back to L1,if desired.

Referring to FIGS. 5 and 6, the expandable interbody device 100 can beassembled by inserting the proximal section 150 of the screw mechanism106 into proximal threaded hole 138 and the distal section 152 of thescrew mechanism 106 into distal threaded hole 140. The external screwthreaded portions 158, 168 engage the threaded holes 138, 140 and thekeyed shaft 170 of the distal section 152 is slid within and engaged, orkeyed, with the internal bore 156 of the proximal section 150. The screwmechanism 106 is then rotated in the direction for contraction until theengagement portion 162 for each section is left exposed (see FIG. 6).The inner structure 104 may then be lowered into the central opening 118of the outer structure 102, with the engagement portions 162 slidinginto the proximal and distal slots 122 of the outer structure 102. Thescrew mechanism 106 is then rotated until the spherical surface 164 ofthe proximal head 158 and the spherical surface 172 of the distal head168 engage the proximal and distal curved or ramp portions 124 of theouter structure 102, shown in FIG. 3. The expandable interbody device100 is now ready to be inserted.

Referring back to FIGS. 3 and 4, in the collapsed configuration theexpandable interbody device 100 may have a height of H1. The proximalhead 160 spherical surface 164 is engaged with the proximal ramp portion124 of the outer structure 102 and the distal head 166 spherical surface172 is engaged with the distal ramp portion 124 of the outer structure102. When the screw mechanism 106 is rotated in a first direction, theproximal head 160 and the distal head 166 can move toward each other(from L1 to L2). While this happens, the spherical surfaces 164 and 172start sliding up the proximal and distal incline ramps 124 andtranslating the inner structure 104 vertically from H1 (collapsedconfiguration) toward H2 (expanded configuration). The expandableinterbody device 100 does not have to be completely extended to H2 andcan be stopped anywhere between H1 and H2, depending on the expansionneeded between the adjacent vertebrae. The proximal and distal ramps 124may also have features that that require more force or less force on thescrew mechanism 106 during expansion. This difference in forces mayprovide tactile feedback to the surgeon as an indication of expansion ofthe expandable interbody device 100.

In some embodiments, the screw mechanism may be a compression screwhaving a proximal section threadably coupled to a distal section, theproximal section having a threaded shaft and the distal section having athreaded bore, such that when the proximal section is rotated, thethreaded shaft engages the threaded bore to shorten or lengthen thedistance between the proximal head 158 and the distal head 168. In thisembodiment, holes 138, 140 would be sized to slideably fit the proximaland distal shafts of the compression screw and would not be threadedholes.

The expandable interbody device 100 may also include a deployment tool.The deployment tool may include various attachment features to enableinsertion of the expandable interbody device 100 into the patient. Forexample, the deployment tool may include arms or clamps to attach to thelongitudinal openings, slots or trenches 120 of the outer structure 102and an actuation device to couple with the head 160 of the proximalsection 150 of the screw mechanism 106. Once the expandable interbodydevice 100 has been inserted and positioned within the intervertebralspace between two vertebrae, the deployment tool may actuate to deployand expand the expandable interbody device 100 by applying a rotationalforce to screw mechanism 106.

In operation, the expandable interbody device 100 may be inserted intothe intervertebral disc space between two vertebrae using an insertionor deployment tool. In some cases, the disc space may include adegenerated disc or other disorder that may require a partial orcomplete discectomy prior to insertion of the expandable interbodydevice 100. The deployment tool may engage with the proximal end of theexpandable interbody device 100. As the deployment tool applies therotational force, the expandable interbody device 100 gradually expandsas described above. The deployment tool may allow an increase in theamount of force that can be applied to the screw mechanism 106 toovercome the friction or interference between the spherical surfaces164, 172 of the distal and proximal heads and ramp portions of the outerstructure 104 during expansion of the expandable interbody device 100.The increase in the force may be used to provide tactile feedback to thesurgeon indicating near complete deployment of the expandable interbodydevice 100.

In some embodiments, more than one expandable interbody device 100 canbe implanted between the adjacent vertebrae of the patient. In suchembodiments, multiple expandable interbody devices 100 can be placed ina side-by-side configuration or any other suitable configuration,thereby creating additional support.

Referring now to FIGS. 7-11, an expandable interbody device 200 can be aspinal implant that includes an outer structure 202, an inner structure204, and a screw mechanism 206. The expandable interbody device 200 canbe movable between a collapsed configuration (show in FIG. 7) to anexpanded configuration (shown in FIG. 8) utilizing the screw mechanism206.

Referring now to FIG. 11, the outer structure 202 can include a topsurface 208, a bottom surface 210, a front side 212, a back side 214,and left and right sides 216. A combination of the sides 212, 214 and216 can form a wall that encloses a central opening 218. The front side212, back side 214, left and right sides 216 may have a varying height,length, thickness, and/or curvature radius. The left and right sides 216may include longitudinal openings, slots or trenches 220 configured tointerface with an insertion and/or deployment tool (not shown) duringimplantation and deployment of the device from the collapsedconfiguration to the expanded configuration. The front side 212 and theback side 214 can have holes 222 sized to slideably fit portions of thescrew mechanism 206, see FIGS. 9 and 10.

The inner structure 204 can include an inner portion 204 a and a lowerflanged portion 204 b. The inner portion 204 a can include a top surface226, a front side 230 a, a back side 232 a, and left and right sides 234a. In the illustrated embodiment, a combination of the sides 230 a, 232a and 234 a forms an outer wall and inner wall that encloses a centralopening 236. The inner portion 204 a outer wall can be configured toslideably fit within the central opening 218 of the outer structure 202,as shown in the figures. The front side 230 a and the back side 232 acan include slots 223 sized to slideably fit the screw mechanism 206threads. The holes 222 of the outer structure 202 are aligned with theslots 223.

The lower flanged portion 204 b of the inner structure 204 can include abottom surface 228, a front side 230 b, a back side 232 b, and left andright sides 234 b. A combination of the sides 230 b, 232 b and 234 bforms an outer wall and inner wall. The inner wall of the lower flangedportion 204 b can also enclose the central opening 236.

On the inner wall of the front side 230 a and back side 232 a areinwardly facing ramps 224 proximate the slots 223 within the centralopening 236 of the inner structure 204 that interface with the screwmechanism 206, shown in FIGS. 9 and 10.

The front sides 230 a, 230 b, back sides 232 a, 232 b, left and rightsides 234 a, 234 b, may have a varying height, length, thickness, and/orcurvature radius. In some embodiments, when the inner structure 204 ispositioned within the outer structure 202, the curvature radius of thetop surfaces 208, 226 can be approximately the same, as shown in FIGS. 7and 9. In other embodiments, the curvature radius of each may bedifferent. In some embodiments, the outer wall of the lower flangedportion 204 b is approximately the same shape as the outer wall of theouter structure 202, as shown in FIGS. 7 and 9. In other embodiments,the outer wall of each may be different. The central opening 236 can beconfigured to receive bone graft material such as allograft and/orDemineralized Bone Matrix (“DBM”) packing.

The top surfaces 208, 226 and the bottom surface 228 of the outer andinner structures 202, 204 can include a plurality of protrusions orteeth 242 (hereinafter, referred to as “teeth”). Teeth 242 can beconfigured to be spaced throughout the top surfaces 208, 226 and thebottom surface 228. As can be understood by one skilled in the art, theteeth 242 can be configured to have variable thickness, height, andwidth as well as angles of orientation with respect to surfaces 208, 226and 228. The teeth 242 can be further configured to provide additionalsupport after the expandable interbody device 200 is implanted in theintervertebral space of the patient. The teeth 242 can reduce movementof the outer structure 202 and inner structure 204 with the vertebraeand create additional friction between the vertebrae and the outerstructure 202 and inner structure 204.

In some embodiments, the teeth 242 on the top surfaces 208, 226 can beconfigured to match when the outer structure 202 and inner structure 204are joined in the collapsed configuration, as shown in FIG. 7. In otherembodiments, the teeth 242 on the top surface 208 of the outer structure202 may have different spacing, configuration, thickness, height, andwidth as well as angles of orientation with respect to the teeth 242 onthe top surface 226 of the inner structure 204. In other embodiments,the outer structure 202 and the inner structure 204 may only have theteeth 242 on surfaces that contact the lower and upper vertebrae in theexpanded configuration. For example, the outer structure 202 may onlyhave teeth 242 on the top surface 208 in contact with the firstvertebrae while the inner structure 204 may only have the teeth 242 onthe bottom surface 228 in contact with the second vertebrae.

In some embodiments, the top surfaces 208, 226 and the bottom surface228 may be a porous or roughened surface, for example, they may beformed of a porous material, coated with a porous material, orchemically etched to form a porous or roughened surface with pores thatparticipate in the growth of bone with the adjacent vertebra.

The proximal section 250 and the distal section 252 of the screwmechanism 206 may be fabricated from any biocompatible material suitablefor implantation in the human spine, such as metal including, but notlimited to, titanium and its alloys, stainless steel, surgical gradeplastics, plastic composites, ceramics, bone, or other suitablematerials. In some embodiments, the proximal section 250 and the distalsection 252 may be formed of a porous material that participates in thegrowth of bone with the adjacent vertebral bodies. In some embodiments,the proximal section 250 and the distal section 252 may include aroughened surface that is coated with a porous material, such as atitanium coating, or the material is chemically etched to form poresthat participate in the growth of bone with the adjacent vertebra. Insome embodiments, only portions of the proximal section 250 and thedistal section 252 may be formed of a porous material, coated with aporous material, or chemically etched to form a porous surface, such asthe upper and lower surfaces that contact the adjacent vertebra areroughened or porous. In some embodiments, the surface porosity may bebetween 50 and 300 microns.

As shown in the figures, the screw mechanism 206 can include a shaft254, a proximal ramped component 264 and a distal ramped component 272.The proximal end of the shaft can include an opening 260 adapted toreceive a driving tool for rotating the shaft 254. The proximal anddistal ramped components 264, 272 can have threaded holes 238, 240 withthreads in opposite directions, hole 238 having a left hand thread andhole 240 a right hand thread, or vice versa. In the illustratedembodiment, the shaft 254 includes proximal section 250 with externalthreads 258, and distal section 252 with external threads 268 inopposite directions, external threads 258 having a left hand thread andexternal thread 268 having a right hand thread, or vice versa, matchingthe threads 238, 240 of the proximal and distal ramped components 264,272. When assembled, proximal ramped component 264 is threaded onto theproximal thread 258 of the proximal section 250 while the distal rampedcomponent 272 is threaded onto the distal thread 268 of the distalsection 252. Having opposite threads on the proximal and distal rampedcomponents 264, 272 matching the proximal and distal sections 250, 252can allow the proximal and distal ramped components 264, 272 to extendor contract along the shaft 254 when the screw mechanism 206 is rotatedor turned to expand or collapse the interbody device (see below).

In use, the proximal and distal ramped components 264, 272 of the screwmechanism 206 can engage the inwardly facing ramps 224 and the proximaland distal sections 250, 252 can extend through slots 223 of the innerstructure 204 and into holes 222 of the outer structure 202 (shown inFIGS. 9 and 10). When the screw mechanism 206 is rotated, the proximaland distal ramped components 264, 272 move along the shaft 254 and slidealong the inwardly facing ramps 224 of the inner structure 204 and theproximal and distal sections 250, 252 slide in slots 223 of the innerstructure 204, while the extreme part of the proximal and distalsections 250, 252 stay within the holes 222 of the outer structure 202.This action translates the inner structure 204 relative to the outerstructure 202 from the collapsed configuration to the expandedconfiguration. If desired, the screw mechanism 206 may be rotated in theopposite direction to translate the inner structure 204 from theexpanded configuration back to the collapsed configuration. This canallow the expandable interbody device 200 to be moved to anotherlocation or reposition if it is expanded in the wrong location and needsto be collapsed prior to moving or repositioning. The shaft 254, theproximal and distal ramped components 264, 272, the outer structure 202and inner structure 204 may be fabricated from any biocompatiblematerial such as stainless steel, or other suitable material.

As discussed above, the external screw threaded portions 258, 268 canmatch the threaded holes 238, 240 of the ramped components 264, 272.Since threaded holes 238, 240 may have thread patterns in oppositedirections, the external screw thread portions 258, 268 may also havematching thread patterns in opposite directions. In some embodiments,the threaded holes and external screw thread portions may have equalpitch, such that during expansion, the proximal and distal end of theouter structure 202 and inner structure 204 translate or move at thesame rate. In other embodiments, the proximal threaded hole and proximalexternal screw thread portion may have a different pitch than the distalthreaded hole and distal external screw thread portion, such that duringexpansion, the proximal and distal ends of the outer structure 202 andinner structure 204 translate or move at different rates. For example,the proximal end of the outer structure 202 and inner structure 204 maytranslate or move at a first rate of speed and the distal end of theouter structure 202 and inner structure 204 may translate or move at asecond rate of speed. The first rate of speed may be faster or slowerthan the second rate of speed. This can allow for some angularitybetween the outer structure 202 and inner structure 204 duringexpansion. The difference between the first and second rates of speedcan allow the user to select an expandable interbody device 200 that hassome angulation after expansion to account for the lordotic curvature ofthe spine.

When the screw mechanism 206 is coupled to the inner structure 204 thedistance between the ramped components 264, 272 can vary in lengthduring interbody expansion (as shown in FIGS. 9 and 10). Initially, thedistance is L3 in the collapsed configuration, shown in FIG. 9. As thescrew mechanism 206 is rotated in a first direction, the distancebetween the ramped components 264, 272 can extend in length to L4 in theexpanded configuration, shown in FIG. 10, due to the threads on theproximal and distal sections and ramped components being threaded inopposite directions. By reversing rotation of the screw mechanism 206 ina second direction, opposite the first, the distance may shorten inlength from L4 back to L3, if desired.

Referring back to FIGS. 9 and 10, in the collapsed configuration theexpandable interbody device 200 can have a height of H3. The proximalramped component 264 can be engaged with the proximal ramp portion 224and the distal ramped component 272 can be engaged with the distal rampportion 224 of the inner structure 204. When the screw mechanism 206 isrotated in a first direction, the proximal ramped component 264 and thedistal ramped component 272 can move away from each other (from L3 toL4). While this happens, the proximal and distal ramped components 264and 272 are forced against the proximal and distal incline ramps 224,sliding the proximal and distal incline ramps 224 in a downwarddirection, translating the inner structure 204 vertically downward fromH3 (collapsed configuration) toward H4 (expanded configuration). Theexpandable interbody device 200 does not have to be completely extendedto H4 and can be stopped anywhere between H3 and H4, depending on theexpansion needed between the adjacent vertebrae. The proximal and distalramps 224 may also have features that that require more force or lessforce on the screw mechanism 206 during expansion. This difference inforces may provide tactile feedback to the surgeon as an indication ofexpansion of the expandable interbody device 200.

The expandable interbody device 200 may also include a deployment tool.The deployment tool may include various attachment features to enableinsertion of the expandable interbody device 200 into the patient. Forexample, the deployment tool may include arms or clamps to attach to thelongitudinal openings, slots or trenches 220 of the outer structure 202and an actuation device to couple with the head 260 of the proximalsection 250 of the screw mechanism 206. Once the expandable interbodydevice 200 has been inserted and positioned within the intervertebralspace between two vertebrae, the deployment tool may actuate to deployand expand the expandable interbody device 200 by applying a rotationalforce to screw mechanism 206.

In operation, the expandable interbody device 200 may be inserted intothe intervertebral disc space between two vertebrae using an insertionor deployment tool. In some cases, the disc space may include adegenerated disc or other disorder that may require a partial orcomplete discectomy prior to insertion of the expandable interbodydevice 200. The deployment tool may engage with the proximal end of theexpandable interbody device 200. As the deployment tool applies therotational force, the expandable interbody device 200 can graduallyexpand as described above. The deployment tool may allow an increase inthe amount of force that can be applied to the screw mechanism 206 toovercome the friction or interference between the proximal and distalramped components 264, 272 and ramp portions 224 of the inner structure204. The increase in the force may be used to provide tactile feedbackto the surgeon indicating near complete deployment of the expandableinterbody device 200.

In some embodiments, more than one expandable interbody device 200 canbe implanted between the adjacent vertebrae of the patient. In suchembodiments, multiple expandable interbody devices 200 can be placed ina side-by-side configuration or any other suitable configuration,thereby creating additional support.

With reference to FIGS. 12-19, some embodiments of the expandableinterbody device 300 can include an upper structure 302, a lowerstructure 304, and a screw mechanism 306. The expandable interbodydevice 300 can be changeable between a collapsed configuration, as shownin FIG. 12, to an expanded configuration, as shown in FIG. 18.

The upper structure 302 can include a top surface 308, a distal side312, a proximal side 314, and left and right sides 316. One or moreslots 318 can extend through the upper structure 302, having an openingon the top surface 308 that is in fluid communication with the bottom ofthe upper structure 302. The one or more slots 318 can be configured toreceive fluids, medication, bone graft material, or other material tohelp in the integration of the interbody device with the vertebrae, suchas with allograft and/or Demineralized Bone Matrix (“DBM”) packing. Thedistal side 312, proximal side 314, and left and right sides 316 mayhave a varying height, length, thickness, and/or curvature radius. Insome embodiments, the upper structure 302 may not have any slots and thetop surface 308 can be closed. In some embodiments, the upper structure302 can have one or more markers 319 to help visualization usingradiation during the implantation procedure. The marker 319 can be madeof a radiopaque material, such as titanium.

The lower structure 304 can include a bottom surface 328, a distal side330, a proximal side 332, and left and right sides 334. One or moreslots 336 can extend through the lower structure 304, having an openingon the bottom surface 328 that is in fluid communication with the top ofthe lower structure 304. In some embodiments, the one or more slots 336may line up with the one or more slots 318 on the upper structure 302,such that the slots extend through the interbody device 300. The one ormore slots 336 can be configured to receive fluids, medication or othermaterial to help in the integration of the interbody device with thevertebrae, such as with allograft and/or Demineralized Bone Matrix(“DBM”) packing. The distal side 330, proximal side 332, and left andright sides 334 may have a varying height, length, thickness, and/orcurvature radius. In some embodiments, the lower structure 304 may nothave any slots and the bottom surface 328 can be closed. In someembodiments, the lower structure 304 can have one or more markers 337 tohelp visualization using radiation during the implantation procedure.The marker 337 can be made of a radiopaque material, such as titanium.The left and right sides 334 may include recesses 320 configured tointerface with a deployment tool during implantation and deployment ofthe device from the collapsed configuration to the expandedconfiguration, as explained below. In some embodiments, the recesses 320can extend through to the inner cavity of the interbody device and canbe used as an access location for delivering fluids, medication or othermaterial, as discussed below.

The top surface 308 of the upper structure 302 and the bottom surface328 of the lower structure 304 can have a roughened surface, such as aplurality of protrusions or teeth 342. The protrusions can be configuredto be spaced throughout the top surface 308 and the bottom surface 328.As can be understood by one skilled in the art, the protrusions can beconfigured to have variable thickness, height, and width as well asangled surfaces. For example, as illustrated in FIG. 15, the top surface308 and bottom surface 328 can have teeth 342 that are angled toward theproximal side. The distal facing side of the teeth 342 are less steepthan the proximal facing side of the teeth 342. This can allow for easyinsertion of the interbody device and help prevent backing out of thedevice from the intervertebral space. The teeth 342 can be configured toprovide additional support after the expandable interbody device 300 isimplanted in the intervertebral space of the patient. For example, thefriction between the vertebrae and the upper structure 302 and lowerstructure 304, provided at least in part by the teeth 342, can helpreduce movement of the interbody device 300 in the intervertebral space.

The upper structure 302 and lower structure 304, or portions thereof,can be made of any of a variety of materials known in the art, includingbut not limited to a polymer such as polyetheretherketone (PEEK),polyetherketoneketone (PEKK), polyethylene, fluoropolymer, hydrogel, orelastomer; a ceramic such as zirconia, alumina, or silicon nitride; ametal such as titanium, titanium alloy, cobalt chromium or stainlesssteel; or any combination of the above materials. The interbody device300 may be made of multiple materials in combination. For example, theupper structure 302 can comprise a polymer, such as PEEK orpolyethylene, and the lower structure 304 can comprise a metal orceramic.

In some embodiments, the upper structure 302 and/or the lower structure304 may be formed of a porous material or have a roughened surface. Thesurfaces may be formed of a porous material, coated with a porousmaterial, or chemically etched to form a porous or roughened surfacewith pores, which may help participate in the growth of bone with theadjacent vertebra. In some embodiments, only portions of the interbodydevice 300 may be formed of a porous material, coated with a porousmaterial, or chemically etched to form a porous surface. For example, atleast some portions of the top surface 308 and/or the bottom surface 328can be coated with a porous material, such as a titanium coating. Insome embodiments, the surface porosity may be at least approximately 50microns and less than or equal to approximately 300 microns.

The upper structure 302 can be configured to slideably fit with thelower structure 304. For example, in the embodiment illustrated in FIG.21 the upper structure 302 has smooth surfaces on its sides that slideagainst smooth surfaces on the sides of the lower structure 304 to forma slide bearing. In other embodiments, the upper structure and lowerstructure can have any of a plurality of different types of functionalcouplers to form a slideable connection.

The distal sides 312, 330 and the proximal sides 314, 332 of the topsurface 308 and bottom surface 328 can have a screw opening 322 thataccepts the screw mechanism 306, as illustrated in FIG. 21. The outersurfaces of the screw opening 322 can have an angled surface 324. Theangled surface 324 can flare outward toward the surface, such that thescrew opening 322 is larger at the surface of the distal side orproximal side than the opening in toward the middle. When the upperstructure 302 and the lower structure 304 are in the collapsedconfiguration, the angled surfaces 324 can form a frustoconical shape.The upper structure 302 can have approximately half of the cone and thelower structure can have approximately half of the cone. The angledsurfaces 324 can interface with the screw mechanism 306 to transitionthe interbody device 300 from the collapsed to expanded configuration,as explained below.

With reference to FIG. 19, the screw mechanism 306 can include aproximal section 350, a distal section 352 and a coupler 380. Thecoupler 380 can have a proximal hole 382 configured to engage theproximal section 350 and a distal hole 384 configured to engage thedistal section 352. The holes 382, 384 can have threads in oppositedirections (i.e., one having a left hand thread and the other a righthand thread). The proximal section 350 can have threads that areconfigured to engage threads in the proximal hole 382 and the distalsection 352 can have threads that are configured to engage threads inthe distal hole 384. In the illustrated embodiment, the proximal section350 and distal section 352 have external threads while the coupler 380has internal threads. In other embodiments, the coupler can haveexternal threads while the proximal section and distal section haveinternal threads. As discussed in more detail below, the threads inopposite directions enable the screw mechanism 306 to contract or extendwhen rotated.

The coupler 380 can include protrusions 386 configured to engage withapertures 388, 390 in the upper structure 302 and lower structure 304,respectively, to prevent the coupler 380 from rotating as the proximalsection 350 of is rotated with a drive tool. In the illustratedembodiment of FIGS. 12-19, the coupler 380 includes two protrusions 386having oval shaped extensions that fit into oval-shaped apertures 388,390. In other embodiments, the protrusions can have any of a variety ofshapes, such as cylindrical or rectangular extensions.

The proximal section 350 can include a threaded portion 358 configuredto engage the threads on the proximal hole 382 of the coupler 380. Theproximal end of the proximal section 350 can include a head 360 with adrive interface 361 adapted to receive a driving tool for rotating ordriving the proximal section 350. In the illustrated embodiment, thehead 360 has a hexagonal shaped cavity for receiving a hexagonal drivewrench. In other embodiments, the head can have any of a variety ofdrive interfaces, such as slotted, cross and polygonal heads. The distalend of the proximal section 350 can have a bore 356 extending along itslongitudinal axis configured to receive a shaft 370 of the distalsection 352. The distal facing side of the head 360 can have an angledsurface 364 configured to slide and press against the angled surfaces324 of the upper structure 302 and lower structure 304. For example, theangled surface 364 can be a tapered cylindrical surface (i.e., afrustoconical shape as illustrated in FIG. 19), with sufficientsmoothness to functionally slide and press against the angled surfaces324.

The distal section 352 can include a head 366 and a threaded portion 368configured to couple with the distal hole 384 of the coupler 380. Thedistal section 352 can also have a shaft 370 extending proximally alongthe longitudinal axis that is configured to slideably couple with thebore 356 of the proximal section 350. As described below, the shaft 370and bore 356 can be keyed, such that when the proximal section 350 isrotated, the distal section 352 also rotates as a unit. The proximalfacing side of the head 366 can have an angled surface 372 configured toslide against the angled surfaces 324 of the upper structure 302 andlower structure 304, as illustrated in FIGS. 20 and 21.

The proximal section 350 and the distal section 352 can be rotatablylinked with a keyed coupling, such that when the proximal section 350 isrotated, the distal section 352 also rotates as a unit. The shaft 370 onthe distal section 352 can have a keyed shape that slideably engageswith the bore 356, on the proximal section 350, which has a matchingkeyed shape. In the embodiment illustrated in FIG. 21, the shaft 370 hasa square cross-sectional shape that slideably engages a bore 356 havinga square cross-sectional shape. Other suitable shapes or geometricconfigurations for a keyed connection between the proximal section 350and distal section 352 may be used in the screw mechanism 306 to achievethe desired results, such as triangular, hexagonal, oval, star-shaped,or other non-circular shape.

In use, the drive interface 361 can be actuated to compress the screwmechanism 306, which engages the upper structure 302 and lower structure304 to move the two structures away from each other from the collapsedconfiguration to the expanded configuration. If desired, the driveinterface 361 may be actuated in the opposite direction to change theinterbody device 300 from the expanded configuration back to thecollapsed configuration. This allows the expandable interbody device 300to be moved to another location or repositioned if it is expanded in thewrong location and needs to be collapsed prior to moving orrepositioning.

With reference to FIGS. 20 and 21, the screw mechanism 306 can vary inlength to change the interbody device from the collapsed configurationto the expanded configuration. Initially, the length of the screwmechanism 306 can be L5 in the collapsed configuration, shown in FIG.20. As the drive interface 361 is rotated in a first direction, theproximal section 350 and the distal section 352 are screwed into thecoupler 380 and the length of the screw mechanism 306 contracts to L6 inthe expanded configuration, shown in FIG. 21. The protrusions 386 on thecoupler 380 are constrained in the apertures 388, 390 on the upperstructure 302 and lower structure 304 to prevent the coupler 380 fromrotating with the proximal section 350 and distal section 352 as thedrive interface 361 is rotated. By reversing rotation of the driveinterface 361 in a second direction, opposite the first, the screwmechanism 306 can be extended in length from L6 back to L5, if desired.

In the embodiment illustrated in FIGS. 20 and 21, in the collapsedconfiguration the expandable interbody device 300 has a distance of H5.The angled surface 364 of the proximal section 350 can contact theproximal ramp portions 324 of the upper structure 302 and lowerstructure 304. The angled surface 372 of the distal section 352 canengage the distal ramp portions 324 of the upper structure 302 and lowerstructure 304. When the drive interface 361 is rotated in a firstdirection, the proximal section 350 and the distal section 352 can movetoward each other from L5 to L6, as explained above. When this happens,the angled surfaces 364 and 372 can push against the angled surfaces 324of the upper structure 302 and lower structure 304, causing the upperstructure 302 and lower structure 304 to separate. The distance betweenthe upper structure 302 and the lower structure 304 can increase from H5(collapsed configuration) to H6 (expanded configuration). The expandableinterbody device 300 does not have to be completely expanded to H6 andmay only be expanded to a partial distance between H5 and H6, dependingon the expansion needed between the adjacent vertebrae. The proximal anddistal angled surfaces 324 can have features that increase resistance toturning of the screw mechanism 306, so that increased actuating forcesare required during select portions of the expansion procedure. Thisvariation of actuating forces can provide tactile feedback to thesurgeon as an indication of expansion position of the expandableinterbody device 300, such as when the interbody device 300 is nearingthe limits of its expansion.

As mentioned above, the threaded portion 358 of the proximal section 350can engage with the proximal hole 382 of the coupler 380 and thethreaded portion 368 of the distal section 352 can engage with thedistal hole 384 of the coupler 380. The proximal hole 382 and distalhole 384 can have thread patterns in opposite directions and the threadportions 358, 368 can have corresponding thread patterns in oppositedirections. In some embodiments, the proximal and distal holes 382, 384and the thread portions 358, 368 may have equal pitch, such that duringexpansion, the proximal side and distal side of the upper structure 302and lower structure 304 translate or move at the same rate. In otherembodiments, the proximal hole 382 and threaded portion 358 of theproximal section 350 may have a different pitch than the distal hole 384and threaded portion 368 of the distal section 352, such that duringexpansion, the proximal side and distal side of the upper structure 302and lower structure 304 translate or move at different rates. Forexample, the proximal side of the upper structure 302 and lowerstructure 304 may translate or move at a first rate of speed and thedistal side of the upper structure 302 and lower structure 304 maytranslate or move at a second rate of speed. The first rate of speed maybe faster or slower than the second rate of speed. This allows for someangularity between the upper structure 302 and lower structure 304during expansion. The difference between the first and second rates ofspeed allows the user to select an expandable interbody device that hassome angulation after expansion, for example to account for the lordoticcurvature of the spine.

The screw mechanism 306 or portions of the screw mechanism 306 can befabricated from any biocompatible material suitable for implantation inthe human spine, such as metals including, but not limited to, stainlesssteel, titanium and titanium alloys, as well as surgical grade plastics,plastic composites, ceramics, bone, and other suitable materials. Insome embodiments, the proximal section 350 and the distal section 352may be formed of a porous material that participates in the growth ofbone with the adjacent vertebral bodies. In some embodiments, the screwmechanism 306 can include a roughened surface that is coated with aporous material, such as a titanium coating, or the material may bechemically etched to form pores that participate in the growth of bonewith the adjacent vertebra. In some embodiments, only portions of thescrew mechanism 306 may be formed of a porous material, coated with aporous material, or chemically etched to form a porous surface, such asthe head 360 of the proximal section 350 and head 366 of the distalsection 352, which may be exposed to the native anatomy after implant.In some embodiments, the surface porosity may be between 50 and 300microns.

In some embodiments, the screw mechanism may be a compression screwhaving a proximal section threadably coupled to a distal section, theproximal section having a threaded shaft and the distal section having athreaded bore, or vice-versa, such that when the proximal section isrotated, the threaded shaft engages the threaded bore to shorten orlengthen the distance between the proximal head and the distal head. Thedistal section can have anti-rotational features, such as for example anoblong head shape, to prevent it from rotating as the proximal sectionis engaged with distal section.

With reference to FIG. 22, a deployment tool 400 can be used to implantthe interbody device 300 into the patient. In use, an incision 10 can bemade on the patient to allow access to the implant site in theintervertebral space 20. The incision can be made for implanting thedevice from the posterior, lateral or anterior directions. The incisioncan be small for a minimally invasive procedure or a larger incision canbe used for an open surgery. Once the implant site is accessed, the twoadjacent vertebrae 30 can be distracted in some situations to open upthe intervertebral space 20. In some situations, the expandableinterbody device 300 can be used to at least partially distract thevertebrae during the implant procedure. In some situations, theintervertebral space 20 may include a degenerated disc or other disorderthat may require a partial or complete discectomy prior to insertion ofthe expandable interbody device 300.

In some configurations, more than one expandable interbody device 300can be implanted between the adjacent vertebrae of the patient. In suchembodiments, multiple expandable interbody devices 300 can be placed ina side-by-side configuration or any other suitable configuration,thereby creating additional support.

With reference to FIG. 23, the deployment tool 400 can have an elongateshaft 406 with a coupling feature toward the distal side 401 that isconfigured to secure an interbody device 300. The proximal side 403 ofthe deployment tool 400 can include a handle 408 attached to the shaft406. A hollow sleeve 410 can be disposed over the shaft 406 such thatthe longitudinal axis of the shaft 406 is generally coincident with thelongitudinal axis of the sleeve 410. The sleeve 410 is movably attachedto the shaft 406 and is configured to translate along the longitudinalaxes. An actuation device 420 can extend through the length of thedeployment tool 400 such that a drive of the actuation device 420 is atthe distal side 401 and a knob is toward the proximal side 403.

The coupling feature includes arms 402 or clamps that engage with therecesses 320 of the lower structure 304 of the interbody device 300. Asshown in the close-up views of FIGS. 25A-B, the arms 402 can haveprotrusions 404 that are configured to be retained by the recesses 320of the interbody device 300. The arms 402 can be moved from an openconfiguration to a closed configuration by manipulation of a translationmechanism 412. In the open configuration, illustrated in FIG. 25A, thesleeve 410 is in its proximal position, allowing the arms 402 to bespread apart sufficiently to fit around the interbody device 300. In theclosed configuration, illustrated in FIG. 25B, the sleeve 410 is in itsdistal position and the walls of the sleeve 410 can compress the arms402 together around the interbody device 300. FIG. 26 shows a close-upview of the arms 402 of the deployment tool 400 coupled to a interbodydevice 300. The arms 402 can have protrusions 404 that engage therecesses 320 on the interbody device 300. In some configurations, thearms 402 can have rails that engage with slots on the interbody device300.

In other embodiments, the deployment tool can be coupled to theinterbody device through other mechanisms, such as rotational (e.g.,threaded) engagement, temporary adhesives, clips, hooks, and the like.The deployment tool 400 can include any of a variety of suitableattachment features to couple the deployment tool 400 to the interbodydevice 300.

With continued reference to FIG. 23, the sleeve 410 can have atranslation mechanism 412 toward the proximal end that is configured toactuate the coupling feature. In the illustrated embodiment, thetranslation mechanism 412 is manipulated by rotation to move the sleeve410 longitudinally relative to the shaft 406. In some configurations,the translation mechanism 412 and the distal part of the sleeve 410 canbe rotatably coupled such that rotation of the translation mechanism 412is translated to linear movement of the distal part of the sleeve 410.In other configurations, the translation mechanism 412 may be rigidlyconnected to the distal part of the sleeve 410 such that the entiresleeve 410 rotates as it translates. The inner surface of thetranslation mechanism 412 can have threads that engage threads 414 onthe shaft 406, as illustrated in FIG. 24. The threaded coupling betweenthe shaft 406 and the sleeve 410 may provide increased mechanicaladvantage for securing the arms 402 around the interbody device 300.

In some configurations, the sleeve 410 can be slideably connected to theshaft 406, in which case the sleeve 410 is manipulated by pushing andpulling. Other means of coupling the sleeve to the shaft such that anactuation of the translation mechanism results in a desiredcorresponding movement of the sleeve are possible and are consideredwithin the scope of the disclosure. The deployment tool 400 can bestraight or curved or a combination of these shapes. In someconfigurations, the deployment tool can have a variable angle shaft suchthat the shape of the tool can be adjusted during use. For example, thedeployment tool can have a hinge that adjusts the bend angle of theshaft for improved fitment of the deployment tool through the incisionand to the target implant site. The deployment tool 400 can be stiff,bendable, or partially stiff and partially bendable. In still otherembodiments, a power source may be provided for hydraulic, pneumatic orother power-assisted manipulation of the sleeve 410.

With continued reference to FIG. 23, the deployment tool 400 can includean actuation device 420 that extends the length of the deployment tool400 for actuating the drive interface 361 from the proximal portion ofthe deployment tool 400. The actuation device 420 can have a distalportion configured to engage the drive interface 361 of the proximalsection 350 of the screw mechanism 306, and a proximal portion foractuation. For example, the embodiment illustrated in FIG. 27 shows anactuation device 420 with an elongate shaft 422 that extends the lengthof the deployment tool 400. A knob 424 can be disposed at the proximalend of the shaft 422 to enable the user to rotate the actuation device420. In other configurations, the proximal end can have a lever, flatprotrusion, drive interface or other suitable rotational mechanism formanipulating the actuation device. The distal end of the shaft 422 canhave a drive 426 configured to engage the drive interface 361. Forexample, the drive 426 can be a hexagonal-shaped driver, or any othershape that is complementary to the drive interface 361 cavity of thescrew mechanism 306.

In operation, the actuation device 420 can be placed through apassageway extending through the center of the deployment tool 400, asillustrated in the cross-sectional view of FIG. 28. After the expandableinterbody device 300 is inserted and positioned within theintervertebral space 20 between two vertebrae 30, the actuation device420 can be used to deploy and expand the expandable interbody device 300by applying a rotational force to the actuation device 420. By rotatingthe knob 424 at the proximal portion of the deployment tool 400, thedrive 426 is also rotated, which in turn rotates the drive interface 361of the screw mechanism 306 and expand the interbody device 300.

As the deployment tool 400 applies the rotational force, the expandableinterbody device 300 gradually expands as described above. The interbodydevice 300 can be expanded until it contacts the two adjacent vertebrae.In some configurations, the interbody device 300 can be used to distractthe two adjacent vertebrae and open up the intervertebral space 20. Theactuation device 420 can advantageously transmit sufficient torque tothe screw mechanism 306 to enable distraction using the interbody device300. In some configurations, the actuation device 420 can have atorque-limiting feature to prevent over-tightening of the screwmechanism 306. For example, the torque-limiting feature can include aspring-loaded clutch mechanism along the shaft 422 of the actuationdevice 420 that can only transmit a predetermined amount of torquebefore the clutch slips. The amount of torque that can be transmittedcan depend on the stiffness of the clutch spring. In other embodiments,the torque-limiting feature can be a portion of the shaft 422 that isconfigured to break at a predetermined torque. In other embodiments, thefeature can be any functional torque-limiting device.

In some embodiments, the deployment tool 400 can be used to deliverfluids, medication or other materials, especially materials that canhelp in the integration of the interbody device with the vertebrae, suchas allograft, Demineralized Bone Matrix (“DBM”) packing, and/or otherbone graft material. The material can also fill up the empty cavitycreated between the upper structure 302 and lower structure 304 uponexpansion, helping to provide support to the vertebrae.

With reference to FIG. 29, a delivery tube 430 can extend the length ofthe deployment tool 400 from the proximal side 403 of the deploymenttool 400 to the proximal section of the screw mechanism 306. Thedelivery tube 430 can have a channel 432 extending the length of thedelivery tube 430 and open at the distal end so that it is in fluidcommunication with the drive interface 361 of the proximal section 350of the screw mechanism 306. In some embodiments, the delivery tube 430is the same as the actuation device except with a channel extendinglongitudinally through it. The actuation device 420 can be a separatecomponent that is removed from the deployment tool 400 to insert thedelivery tube 430. In some embodiments, the delivery tube 430 andactuation device 420 are the same component that serves both functions.For example, the actuation device can have a distal end configured toengage the drive interface 361 and a channel extending through itslength.

In some configurations, the material is forced through the deliverychannel 432 by a pressurized delivery system. For example, a poweredcompressor can be attached to the proximal end of the delivery tube 430to push material through the delivery channel 432 and into the cavity ofthe interbody device 300. In some configurations, the fluids, medicationor other material is delivered to the interbody device 300 by manuallypushing the material through the delivery tube, for example by using apush rod. The push rod can be an elongate shaft that closely fits theinside diameter of the delivery channel. The push rod can have a forcemultiplier to provide increased mechanical advantage for pushing thematerial through the delivery channel. For example, the push rod can bethreadedly engageable with the delivery tube such that the material ispressed through the delivery channel as the push rod is screwed onto thedelivery tube. In another example, the push rod can include a ratchetinghandle that provides leverage to help push material through the deliverychannel.

With reference to FIGS. 30 and 31, the proximal section 350 of the screwmechanism can have injection holes 359 that extend from the driveinterface 361 to the angled surface 364. The proximal section 350 canhave one, two, three, or more injection holes 359. In the illustratedembodiment, the injection holes 359 are round holes. In otherembodiments, the injection holes can be any of a variety of shapes, suchas square, oval or polygonal. The injection holes can provide fluidcommunication between the delivery channel 432 and the interior of theinterbody device 300. In the illustrated embodiment of FIG. 23, thedelivered material travels through the channel 432, into the driveinterface 361, through the injection holes 359 and into the cavitybetween the upper structure 302 and lower structure 304. The materialcan fill up the cavity and also travel through the slots 318 in theupper structure 302 and the slots 336 in the lower structure 304 to comeinto contact with the vertebrae.

As illustrated in cross-sectional top view of FIG. 32, the fluids,medication or other materials can be delivered through the arms 402′ ofthe deployment tool 400′. Channels 432′ can extend through the arms 402′and have an opening at the tips of the arms 402′. When the deploymenttool 400′ is coupled with the interbody device 300, the opening in thearms 432′ can be positioned in the recesses 320 of the lower structure304, placing the channels 432′ in fluid communication with the interiorcavity of the interbody device 300. This configuration advantageouslyallows the materials to be delivered to the interbody device 300 throughexisting components without having to introduce a separate pathway.

The deployment tool can be made of any appropriate material for theparticular part. Materials can include, but are not limited to,stainless steel, surgical steel, cutlery steel, tool steel, cobalt andits alloys, nickel and its alloys, chromium and its alloys, titanium andits alloys, zirconium and its alloys, aluminum and its alloys, magnesiumand its alloys, polymers, elastomers, and ceramics. Ceramics mayinclude, but are not limited to silicon carbide, silicon oxide(s),silicon nitride, aluminum oxide, alumina, zirconia, tungsten carbide,other carbides.

The sizes of the interbody device and deployment tool are appropriatefor treating the particular bone. Smaller devices can be used forsmaller vertebra and larger devices for larger vertebra. In addition,the device can be used on bones other than the vertebra and on bones forhumans and non-humans.

A method of implanting the interbody device 300 comprises coupling theinterbody device 300 to the deployment tool 400. The deployment tool 400can engage the interbody device 300 by manipulating the translationmechanism 412 to clamp the arms 402 onto the recesses 320. An incision10 can be made on the patient to allow access to the implant site in theintervertebral space 20. The incision can be made for implanting thedevice from the posterior, lateral or anterior directions. The incisioncan be small for a minimally invasive procedure or a larger incision canbe used for an open surgery. In some situations, two adjacent vertebrae30 can be distracted to open up the intervertebral space 20. In someconfigurations, the expandable interbody device 300 can be used to atleast partially distract the vertebrae during the implant procedure.

A user can hold the handle 408 of the deployment tool 400 to implant theinterbody device 300 in the intervertebral space 20. Once the interbodydevice 300 is positioned between adjacent vertebrae, the actuationdevice 420 can be rotated to turn the drive 426 and engage the screwmechanism 306. The screw mechanism 306 changes length from a firstlength to a second length such that the proximal frustoconical surface364 engages the upper proximal angled surface and the lower proximalangled surface, and the distal frustoconical surface 372 engages theupper distal angled surface and the lower distal angled surface toexpand the upper structure 302 and the lower structure 304 from a firstdistance to a second distance.

In some embodiments, materials such as fluids, medication, bone graftmaterial, allograft and/or Demineralized Bone Matrix (DBM) can bedelivered to the interior cavity of the interbody device 300. Thematerial can be delivered through a delivery tube 430 and into theproximal section 350 of the screw mechanism 306 or through the arms 402of the deployment tool. In other embodiments, the material can bedelivered through other paths to reach the cavity of the interbodydevice 300.

To release the interbody device 300, the translation mechanism 412 isrotated. Rotation motion of the translation mechanism 412 is transferredto the sleeve 410 as a linear motion away from the arms 402 via thethreaded connection. The arms 402 can move apart to release theinterbody device 300 and allow removal of the deployment tool 400 fromthe patient.

In some configurations, more than one expandable interbody device 300can be implanted between the adjacent vertebrae of the patient. In suchembodiments, multiple expandable interbody devices 300 can be placed ina side-by-side configuration or any other suitable configuration,thereby creating additional support.

In some embodiments of the deployment tool 400, the movement of thetranslation mechanism 412 and/or actuation device 420 can be effected bymanual force applied by a person, such as by his or her hands, oralternatively it can be supplied or supplemented with a motor,pneumatics, hydraulics, springs, and/or magnetics. Some embodiments ofthe tool may comprise a squeeze handle for actuating the tool. Otherembodiments of the tool can include closing mechanisms that includecompound leverage, ratcheting, and/or multistep closing.

Although certain embodiments, features, and examples have been describedherein, it will be understood by those skilled in the art that manyaspects of the methods and devices illustrated and described in thepresent disclosure may be differently combined and/or modified to formstill further embodiments. For example, any one component of the deviceillustrated and described above can be used alone or with othercomponents without departing from the spirit of the present disclosure.Additionally, it will be recognized that the methods described hereinmay be practiced in different sequences, and/or with additional devicesas desired. Such alternative embodiments and/or uses of the methods anddevices described above and obvious modifications and equivalentsthereof are intended to be included within the scope of the presentdisclosure. Thus, it is intended that the scope of the presentdisclosure should not be limited by the particular embodiments describedabove, but should be determined only by a fair reading of the claimsthat follow.

What is claimed is:
 1. A method of implanting an expandable interbodydevice comprising: positioning the expandable interbody device betweenadjacent vertebrae, wherein the expandable interbody device comprises:an upper structure configured to abut a superior vertebra; a lowerstructure configured to abut an inferior vertebra; and a screw mechanismbetween the upper structure and the lower structure, the screw mechanismcomprising a proximal portion, a distal portion and a coupler at leastpartially between the proximal portion and the distal portion; androtating the proximal portion and the distal portion as a unit to changea length of the screw mechanism from a first length to a second length,wherein the coupler is prevented from rotating by at least oneanti-rotational feature when the proximal portion and the distal portionare rotated; wherein a distance between the upper structure and thelower structure changes from a first height to a second height as thelength of the screw mechanism changes from the first length to thesecond length.
 2. The method of claim 1, wherein the first heightcorresponds to a collapsed configuration with the upper structureproximate the lower structure and the second height corresponds to anexpanded configuration with the upper structure distanced from the lowerstructure.
 3. The method of claim 1, wherein the proximal portioncomprises a proximal frustoconical surface, the distal section comprisesa distal frustoconical surface, and the coupler comprises a proximalside configured to engage the proximal section and a distal sideconfigured to engage the distal section.
 4. The method of claim 1,wherein the proximal portion comprises first threads wound in a firstdirection configured to engage a proximal threaded hole in the coupler,and the distal portion comprises second threads wound in a seconddirection, opposite the first direction, configured to engage a distalthreaded hole in the coupler.
 5. The method of claim 4, wherein thefirst threads and the second threads have an equal pitch, such that whenthe screw mechanism is actuated, a proximal end of the interbody devicechanges height at a same rate as a distal end of the interbody device.6. The method of claim 4, wherein the first threads and the secondthreads have a different pitch, such that when the screw mechanism isactuated, a proximal end of the interbody device changes height at adifferent rate than a distal end of the interbody device.
 7. The methodof claim 1, wherein the distal portion comprises a keyed shaftconfigured to slideably engage with a matching keyed bore on theproximal portion.
 8. A method of implanting an expandable interbodydevice comprising: positioning the expandable interbody device betweenadjacent vertebrae, wherein the expandable interbody device comprises:an upper structure configured to abut a superior vertebra; a lowerstructure configured to abut an inferior vertebra; and a screw mechanismbetween the upper structure and the lower structure, the screw mechanismcomprising a proximal portion, a distal portion and a coupler at leastpartially between the proximal portion and the distal portion; androtating the proximal portion and the distal portion as a unit to changea length of the screw mechanism from a first length to a second length,wherein the coupler is prevented from rotating by at least oneanti-rotational feature that engages the upper structure or the lowerstructure when the proximal portion and the distal portion are rotated;wherein a distance between the upper structure and the lower structurechanges from a first height to a second height as the length of thescrew mechanism changes from the first length to the second length. 9.The method of claim 8, wherein the first height corresponds to acollapsed configuration with the upper structure proximate the lowerstructure and the second height corresponds to an expanded configurationwith the upper structure distanced from the lower structure.
 10. Themethod of claim 8, wherein the proximal portion comprises a proximalfrustoconical surface, the distal section comprises a distalfrustoconical surface, and the coupler comprises a proximal sideconfigured to engage the proximal section and a distal side configuredto engage the distal section.
 11. The method of claim 8, wherein theproximal portion comprises first threads wound in a first directionconfigured to engage a proximal threaded hole in the coupler, and thedistal portion comprises second threads wound in a second direction,opposite the first direction, configured to engage a distal threadedhole in the coupler.
 12. The method of claim 11, wherein the firstthreads and the second threads have an equal pitch, such that when thescrew mechanism is actuated, a proximal end of the interbody devicechanges height at a same rate as a distal end of the interbody device.13. The method of claim 11, wherein the first threads and the secondthreads have a different pitch, such that when the screw mechanism isactuated, a proximal end of the interbody device changes height at adifferent rate than a distal end of the interbody device.
 14. The methodof claim 8, wherein the distal portion comprises a keyed shaftconfigured to slideably engage with a matching keyed bore on theproximal portion.